patman: Adjust command.Output() to raise an error by default

It is more useful to have this method raise an error when something goes
wrong. Make this the default and adjust the few callers that don't want to
use it this way.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/patman/command.py b/tools/patman/command.py
index d586f11..d1f0ca5 100644
--- a/tools/patman/command.py
+++ b/tools/patman/command.py
@@ -104,8 +104,9 @@
         raise Exception("Error running '%s'" % user_pipestr)
     return result
 
-def Output(*cmd):
-    return RunPipe([cmd], capture=True, raise_on_error=False).stdout
+def Output(*cmd, **kwargs):
+    raise_on_error = kwargs.get('raise_on_error', True)
+    return RunPipe([cmd], capture=True, raise_on_error=raise_on_error).stdout
 
 def OutputOneLine(*cmd, **kwargs):
     raise_on_error = kwargs.pop('raise_on_error', True)